Electronic registers for binary digital computing apparatus



March 12, 1957 J. BRUCE ETAL 2,785,304

ELECTRONIC REGISTERS FOR BINARY DIGITAL COMPUTING APPARATUS Filed Sept. 12, 1952 2 Sheets-Sheet 1 9 6 i 2; 24 E g91 6a 2 7o. 26 3 4 27 2 a I 30. 4a

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INVENTORS March 12, 1957 J, BRUCE HAL 2,785,304

ELECTRONIC REGISTERS FOR BINARY DIGITAL COMPUTING APPARATUS Filed Sept. 12. 1952 2 Sheets-Sheet 2 INVENTORSI:

JONN BRUCE KEITH GORDON HUNTLEY ERIC LAWRENCE CASLING WHITE A11 ney United States Patent ELECTRONIC REGISTERS FOR BINARY DIGITAL COMPUTING APPARATUS Claims priority, application Great Britain September 15, 1951 7 Claims. (Cl. 259-27) This invention relates to electronic registers for binary digital computing apparatus, and especially to shifting registers for apparatus operating in the time serial mode.

The invention relates in particular to electronic registers of the delay storage type and where reference is made herein and in the claims to a register of the delay storage type it is to be understood to mean a register including at least two triggers each .of which has two states of equilibrium and comprises two valves with anodes and control electrodes cross-coupled to produce two equilibrium states of the trigger with only one valve conducting in each state ofthe trigger, and coupling means for transferring the state of a first of said trigger to the second, if different therefrom, under the control of transfer pulses, said coupling means includ ing unilaterally conductive paths which are rendered conducting by a transfer pulse, in dependence upon the states of the triggers, the coupling circuit also including a storage device whereby the second trigger is left in the previous state of the first trigger on the termination of a transfer pulse.

One form of electronic register of the delay storage type is described in Electronic Engineering for December, 1950, page 495 et seq., with reference to Figure 10, the register being intended for use as a shifting fer pulses and for reading the numberis fed out of the last trigger when a further series of'transfer pulses 'is applied. In the register described in said publication the coupling between two triggers is from the anodes .of the valves of one trigger to the control electrodes of the alternate valves of the next trigger, so that in the intervals between shift pulses, the unilaterally conductive devices have applied to them back potential which may be of the order of the positive polarising potential for the anodes of the valves of the triggers, and atthe least is the potential difference which exists between the anode of a conducting trigger valve and the control electrode of a non-conducting trigger valve. This restricts the choice of elements for use as the unilaterally conductive devices to thermionic valves, which are undesirable on' account of their bulk and their consumption of heatercurrent, which it is important to keep toua minimum when large numbers of similar circuits are involved; Furthermore shift pulses of large amplitude are required in the register described in the aforesaid publication.

2,785,304 Patented Mar. 12 1957 The object of the present invention is to provide an improved electronic register of the delay storage type in which crystal diodes can be used in the coupling means between the triggers and/ or in which shift pulses of smaller amplitude can be used than in the above described form of register.

In order that the said invention may be clearly understood and readily carried into effect, the same will now be more fully described with reference to the accompanying drawings:

Figure 1 illustrates diagrammatically one form of electronic shifting register according to the present invention,

Figure 2 illustrates another form thereof,

Figure 3 illustrates a modification of Figure 2.

' Figure 4 illustrates a modification of Figure 3.

Referring to Figure 1, two stages of the shifting register are illustrated therein, the stages respectively comprising thermionic valve triggers denoted in general by the reference numerals 1 and 2. It is to be understood, however, that the complete register will comprise a large number of such triggers connected in succession, the

number being dependent upon the number of binary digits to be stored in the register. The triggers are of a known form having two stable states of equilibrium,

the trigger 1 comprising for example two vacuum valves 3 and 4 enclosed in a single envelope and having their anodes and control electrodes cross-coupled by resistances 5 to 10 as shown. Resistances 11 and 12 are also connected in the cathode leads of the valves 3 and 4. The trigger 2 is generally the same as the trigger 1 and the corresponding parts are denoted by the same reference numerals but are distinguished by the suflix a. The anode load resistances 5, 5a, 8 and 8a of the valves are returned to a positive potential source of +300 volts, the control electrodes are returned via resistances 7, 7a, 10 and 16a to a negative potential source of 300 volts, while the cathode resistances 11, 11a, 12 and 12a are taken to ground. The only distinction between the successive triggers is that the cathode resistances are progressively varied in value so that the cathode potential of a conducting valve in a given trigger is about 2 volts less than the cathode potential of a conducting valve in the next preceding trigger. The cathode-of the valve 3 is coupled to the control electrode of the valve 3o via a time constant circuit, consisting of a resistance 13 and condenser 14, and a unilaterally conductive device 15 in the form of a germanium diode. The condenser 14 has one electrode connected as shown to a bus bar 16 by means of which transfer pulses can be applied, one such pulse being indicated by the reference 17. The time constant of 13 and 14 is arranged to' be long relative to the duration of the transfer pulses but short relative to the intervals between the transfer pulses, which, as will be understood, is the digit interval of the register. The junction of 13 and 14 is connected by a resistance 18, large compared with resistance 13, to the +300 volt source so thatthe cathode of the diode 15 is maintained at a potential 10. volts positive with respect to the cathode of the valve 3, -irrespective of the state of the valve 3. The cathode of the valve 4 is connected to the control electrode of 'the valve 4:: by elements 13a, 14a, 15a and 18a simireasses the valve a is at (say) +8 volts and the control electrode of the valvdaa is at slightly higher potential. The d e vice 15 is therefore just not conducting. On the other hand the cathode of the valve@ is at volts the cathode of the device. a is at .volts,..while ,the con-' Ttrel electrode of the valve 4a is at groundv potential. The device-15a istherefore also held-oft, aboutZOwolts be- .ing'the maximum baclepotential appliedvto thedevices 15 and 15a. The transfer pulses 1 7.are1ofnegative polarity with an amplitude of about 20 VQltS. --On the application of a pulse, both the devices 15 and 15a conduct and the control electrode of the ,valve Ziais carried to a potential of IO volts and thecontrolelectrode 9f "the Y' ll? a c i d to pcteetia to l ero-vol s rresr ctir Bf the Pr 9u .-s;9n i i. 2ns.p ther ve 3a and 4a. This situation is maintained until the end (of the Pulse 17, byyi u lo thetimeconst ntsoflitand 14 ,to the potential ,of the respective cathodes.

applied. Moreover,.thetimeconstant of the resistance 9ii aiidth condenser lm maintains the control electrode of the valve 4:: at a sufficient positive potential to render this valve conducting when the transfer pulse ceases so that at the end of the pulse the circuit 2 assumes the alternate state,,that is ,state ,0. It maylhesadyantageons to interpose additionalsmoothing' circuits between the valve anodes and the respective resistances 23 and 23a and also to. return the cathodesgof' the. devicesslsx andiSa tona. potential, slightly difierent :from;:the generalzpositive polarising potential. i

The arrangement shown in-Figure2 maybe-modified by returning the unilaterally conductive devicesand 251110 t e t n rruls bu .batand arr n in tbs normal potential of the latter is at or near the positive polarising potential and that'itfis :tedwithnegative transfer pulses of about 10 volts; In this case only that device will conductwhich-isfed fro rntheanode of the valve of the preceding trigger which is non-conducting and the negative transfer pulse willfbe passedthroughjt to ,triggeitthe next's ta gel if the valve concerned is not already conducting.

In the modification 'ofFigure 2illustrated in Figure-3L coupling is between the anodes oflike valvesin the r trigfll'he ftorml of ;the invention illustrated in :Figure'2 is ,generallyofthe same construction as-described-with refcrencegtoeFigure ,1 .and. corresponding parts havel bcen indicated bysthe :samereference numerals. However, in \the case .of Figurex2, coupling is between-the anodes ts 1,a'nd 2, i. e. between valves 3 and3a and betwee n valves 4 andfia and the positions of fthecondensers 24 and 24a are'interchanged with the devices 25 and 251;,1the

condensers 24,and 24a being, moreover, connected vatone side'to the transfer pulse busbar 16. The junction of the condenser 24 and, the unilaterally conductive device 25, and the junction of 24a and 25a, areconnected by resistances 28, and'28a to a line 29 which serves to apply of .thevalves :3 andAa, and 4 and 3a respectively. The

valvesjtv and 4. and vsimilarlythe valves 3:: and-4a have common cathode resistancesl? and 20, and the-trans .fer pulse bus bar 16 is connected in common to all the cathodes byrresistancesfllv and '22 as indicated-the trans- ,fer pulses 17 being of positive polarity and 30 volts am- :Ioflescribeithe operation, of the arrangement, it 'will V hegasstunedlthat both the circuits! and 2 are in statefO',

thattis the valves 3 and 31.1 are non-conducting and the valves r4zand a are conducting. Condensers Mandi 421 tarcrcharg'ed tothe potential 'difierence 'hetweenthe "respcctivevan'odes,:the lefthancl-electrode of the condenser -24 being more-positivethaxi' itsright-han'd electrode, and

vice versa in' the case cf the condenserQ-ta. If a posinvie transfer pulse 13 isnow applied toithe bus bar 15, and thence to- 'the 'cathodesof valves 3a and 4a" (and also to'cathodes of an other trigger valves) it tends to 7 reversethestateof'the trigger 2, cutting offboth valves 3:: and 4dffor=the duration ofthe pulse, the transfer pulse only'requiring'an amplitude sufiicient to switch off both valves. The {anode of rise to +3G0-volts; tends to bring the lett hand electrode of the condenser 24 to a potentialwell above -+3'00- volts but this' section isprevented' by conduction through the device 25 so that the anode of the valvej' ltz the valve 4:! thereforetends to is prevented from rising and the tendency for a reversal of state of'the trigger 2 is resisted, the valve 4a bein glrestored to the conducting condition on the termination of the transfer pulse. If, on the other hand, prior to the occurrence'of' the pulse, the circuit i is in state Oas 'described while the circuit 2 is'in state 1, that isj'to say the t valve is conducting, neither of the condensers 24 or 24a is charged so" that the anode potential of thevalve 3a 1S-h0t prevented from rising when a transferpulse is apositive bias potential. Transfer pulses 17 are to the bus bar 16 with negative polarity.

'In this'modification the bias potentialwhich is applied 7 by .the line 29 ,is such that if the coupled anodes of the triggers lIand v2 are at the same potential, atransfer pulse ,17 is prevented from affectin'gthc trigger'z, which 'is what ,is.wantedsince' no change of state of the trigger 2 is required. on the other hand, if the triggers 1 and 2 are in clifierent states one anode of triggerl will be at a lower potential than the corresponding anode in trigger 2. Y Hence on the application of a transfer pulse, the relevant device conducts and the state of trigger 2 is changed to conform to that of trigger; ,at-thetimepf application, of the, pulse.

lath mod ion 0t F gure 3 whi islillnst a e i Fi r 1 1 trigger va ve 3,3 4 and 4a. h ve Ql1 a re t nc 7 .7 2 a, 0- n 30a conne te :in .the a 1 de1e ds as h wn; in eries Withihe ano'detresistances 5,1511, 8r ian .8a, Thezp sitive biasctcquired atthe 113th.

'pdes ofthe unilaterally conductive devices, 725M251; ;.is

provided. by connecting ,the-,resis tance.;23 tozthe junction ofslics stancesiand: 29.,and by connecting the resistance j-2f3aato the junctionoflesistances, .8 and Ell-respectively.

bias so, applied :is :suflicient just-to maintainflthe device :25 say) u non-conducting V .in the event .:that. the valve 3 ,is conducting and the, valve 3a, non-conducting, and assimilar considerations applies to the. device: 25a. It vwill be understood that the couplings from the trigger :2 to the nextctrigger' lead from, the junction-ofi -the resist'ances 5a and 29mm the junction of resistances la andr30q respectivelyr i Ina-practical; form of the arrangement shownin Fig :4,' t e components have the-following values:

liesistances 5, 8. -,--ohr.n "17, 10 R sidenc 6--.----V---,---' do 39,000 Rcsistancesplfl, 1",- c do ,c8410!) The valves 3 and'4 are constituted by a double of type 12AT7, The corresponding components ofeach greases trigger have the same values and the arrangement operates with transfer pulses of an amplitude of about 15 volts.

While the invention has been described as applied to shifting registers for transferring numbers one digit per shift, as in computors operating in the time-serial mode, the invention may also find application to registers operating in the parallel mode, where it is required to transfer the contents of one register bodily to another register in a single sideways shift. In this case the couplings would be between corresponding triggers in the difierent registers.

From the foregoing description, it will be appreciated that in all the registers illustrated, there is a direct coupling from one electrode of one valve of one trigger to a like electrode of one valve of the second trigger, the expression like electrode being intended to indicate that the coupled electrodes are either high potential electrodes, such as anodes, or low potential electrodes such as control electrodes or cathodes. Moreover the term direct coupling is intended to indicate that the coupling is direct from the first electrode specified to the second electrode specified and is not made by way of an intermediate electrode as for instance if an anode of one valve is coupled to the control electrode of another valve and thence to an anode by virtue of the cross coupling of the valves of the trigger. Such a coupling would not constitute a direct coupling from anode to anode.

What we claim is:

1. An electronic register comprising at least two triggers, each trigger comprising two valves each having an output electrode, a control electrode and a cathode, and a cross-coupling from the output electrode of each valve to the control electrode of the other valve to produce two equilibrium states of the trigger with only one valve conducting in each state, an impedance in the cathode circuit of each trigger valve, a first path including the series combination of a resistance and a unilaterally conductive device connected from the cathode circuit of one valve of one trigger to the control electrode circuit of one valve of the second path including the trigger, a second series combination of a resistance and a unilaterally conductive device connected from the cathode circuit of the other valve of the first trigger to the control electrode circuit of the other valve of the second trigger, and means for biasing said unilaterally conductive devices to maintain the respective devices normally nonconducting in any equilibrium state of said triggers, a source of transfer pulses, and storage means for applying the pulses from said source to said junctions to render said devices conducting in dependence upon the equilibrium states of said triggers to produce a change of state of said second trigger if said triggers are initially in unlike states.

2. An electronic register comprising at least two triggers, each trigger comprising two valves each having an output electrode, a control electrode and a cathode, and a cross-coupling from the output electrode of each valve to the control electrode of the other valve to produce two equilibrium states of the trigger with only one valve conducting in each state, a first path including the series combination of a resistance and a storage device connected from the output electrode circuit of one valve of one trigger to the output electrode circuit of one valve of the second path including the trigger, a second series combination of a resistance and a storage device connected from the output electrode circuit of the other valve of the first trigger to the output electrode circuit of the other valve of the second trigger, a source of bias potential, different unilaterally conductive paths from said bias source to the junctions of the resistances and storage devices in said series combinations, said bias potential being predetermined to maintain said unilaterally conductivepaths normally nonconducting in any equi librium state of said triggers, a source of transfer pulses, and means for applying pulses from said latter source to said triggers to render said unilaterally conductive paths conducting in dependence upon the equilibrium states of said triggers and produce a change of state of 7 gers, each trigger comprising two valves each having an output electrode, a controlelectrode and a cathode, and a cross-coupling from the output electrode of each valve to the control electrode of the other valve to produce two equilibrium states of the trigger with only one valve conducting in each state, a first path including the series combination of a resistance and a unilaterally conductive device connected from the output electrode circuit of one valve of one trigger to the output electrode circuit of one valve of the second trigger, a second path including the series combination of a resistance and a unilaterally conductive device connected from the output electrode circuit of the other valve of the first trigger to the output electrode circuit of the other valve of the second trigger, means for biassing said unilaterally conductive devices to maintain the respective devices normally nonconducting in any equilibrium state of said triggers, a source of transfer pulses, and storage means for applying pulses from said source to said paths to render said devices conducting in dependence upon the equilibrium states of said triggers and produce a change of state of said second trigger if said triggers are initially in unlike states.

5. An electronic register comprising at least two triggers, each trigger comprising two valves each having an output electrode, a control electrode and a cathode and two potential divider chains connected from a source of relatively high potential to a source of lower potential, the output electrode of one valve and the control electrode of the second valve being connected respectively to higher and lower potential points on one divider chain and the output electrode of the second valve and the control electrode of the first valve being connected respectively to higher and lower potential points on the second divider chain whereby said valves are cross-coupled to produce two equilibrium states of the trigger with only one valve conducting in each state, a first path including the series combination of a resistance and a unilaterally conductive device connected from a point in one divider chain in one trigger to a point in one divider chain in the second trigger, a second path including the series combination of a resistance and a unilaterally conductive device connected from a point in the other divider chain of the first trigger to a point in the other divider chain in the second trigger, the points of connection of said paths to the divider chains being predetermined to bias said unilaterally conductive devices and maintain said devices normally nonconducting in any equilibrium state of said triggers, a source of transfer pulses, and capacitive means for applying pulses from said source to said path to render said devices conducting in dependence upon the equilibrium states of said triggers and produce a change of state of the second trigger if said triggers are initially in unlike states.

6. A register according to claim 5, each of said paths being connected from a point on the divider chain of the first trigger located between the respective output electrode and said potential source to the point of connection of the respective output electrode on the divider chain of the second trigger.

7. An electronic register comprising at least two triggers, each trigger comprising two vacuum valves each having an output electrode, a control electrode and a 

